The present application relates to a grounding assembly for use in an electronic device that includes a shaft rotatably mounted in an insulated environment. More particularly, the present invention relates to a grounding assembly for use with a rotatable shaft in a printer assembly and will be described with particular reference thereto. However, it is to be appreciated that the grounding assembly may be used in other similar environments and applications.
Many electronic devices, including many printer devices, include one or more shafts rotatably mounted to an insulated frame structure. Bearings are often employed to rotatably support and connect such a shaft to the frame structure. One problem frequently encountered in these types of arrangements is the build-up of an electrical charge in the shaft. For example, in a printer device shafts are used that engage or have components therein that engage moving objects. One specific example is an exit shaft on a printer device. An exit shaft is involved with moving paper out of the printer device and, in this capacity, often picks up a charge. Particularly, when such shafts are metallic and the structure supporting the shaft is insulated or non-conductive, the charge can build-up to undesirable levels over time.
When a charge builds up in a shaft, or in the bearing or bearings supporting the shaft, but is not dissipitated because the structure the shaft is mounted to is insulated, the possibility of an undesirable electrical static discharge (ESD) is increased. If an ESD occurs, a user of the printer device can be shocked and/or one of the electrical components of the printer device could become damaged and/or unusable. Grounding assemblies are known to be used with shafts and bearings for reducing the likelihood of an ESD. Such grounding assemblies are in electrical contact with at least one of the shaft and its bearings and are suitably electrically connected to dissipitate any significant charge occurring in the shaft or its bearings.
Some prior art grounding assemblies incorporate fingers for better grounding the electrically conductive shaft and its bearings. These fingers often extend axially between the shaft bearings and the insulated structure receiving the bearings. Fingers of many prior art grounding assemblies were often replete with deficiencies. For example, the fingers sometimes included an angle to bend the finger into contact with the bearing. These bends were often sharp which resulted in excess deformation of the finger and poor structural contact between the finger and the bearing. More specifically, excess deformation reduced any spring force in the fingers resulting in poor contact. When multiple fingers are used, they are known to sometimes deform in different amounts relative to one another resulting in varying qualities of contact and preventing the bearing from properly centering within a designated hole in the surrounding structure. Thus, there is a need for a grounding structure that maintains acceptable electrical contact and/or assists in centering a shaft bearing within a designated hole.
Moreover, some prior art grounding assemblies have configurations that made assembly of the shaft, bearings and grounding assemblies into an electric device difficult. More specifically, some previous grounding finger geometries do not allow the bearing to begin to be seated in an aperture of the surrounding structure before it made contact with and began to yield the grounding part. As a result, it is often difficult to easily and efficiently install bearings into frame structure apertures when grounding assemblies are employed.